1. Field of the Invention
This invention relates to a method of detecting concentration of contamination on a semiconductor wafer, and especially relates to a method of detecting concentration of contamination on a semiconductor wafer which is effective to sensitively detect concentration of contamination on a semiconductor wafer.
2. Description of the Prior Art
The WSA (wafer surface analysis) method has been used as a method of detecting metal contamination such as Fe or Cu formed on a semiconductor wafer. The WSA method is carried out in a series of the following steps.
1) A hydrophobic surface is formed on a semiconductor wafer by dissolving a natural oxide film formed on the semiconductor wafer. PA1 2) A medical fluid is dropped on the hydrophobic surface. PA1 3) The medical fluid dropped on the hydrophobic surface is moved along the surface of the semiconductor wafer so that the medical fluid contains therein contaminants attached to the surface of the wafer. PA1 4) The medical fluid which contains the contaminants is collected. PA1 5) The medical fluid collected in the step 4 is analyzed with an analysis device to obtain the concentration of contamination. PA1 6) The concentration of contamination on a product wafer is determined based on the concentration of contamination obtained in the step 5.
The concentration of contamination down to a level of 10.sup.9 -10.sup.10 (atoms/cm.sup.2) can be detected according to the WSA method. However, to detect the contamination on a semiconductor wafer in the WSA method is gradually more difficult as contamination on semiconductor wafers which have been cleaned becomes lower with the improvement of the cleaning technology.